Lusi Safriani

Charge Carrier Dynamics of Active Material Solar Cell P3HT:ZnO Nanoparticles Studied by Muon Spin Relaxation (μSR)

Poly (3-hexylthiohene) (P3HT) has attracted much attention due to their chemical and thermal stability as well as their potential to be used as an active material in solar cells. Recently, hybrid solar cell has been developed due to the combining advantages of organic material (P3HT) and inorganic material such as nanoparticle zinc oxide (ZnO). ZnO is an inorganic material with high electron mobility and easy to prepare as electron acceptor to dissociate excitons formed in conjugated polymer as the active material of solar cells. ZnO also can be prepared as a nanoparticle that can resolve a problem of small exciton diffusion length of P3HT. However, the clearly explanation about the effect of ZnO to the charge carrier dynamics in P3HT is not fully understanding yet. We have studied charge carrier dynamics in active material of solar cell P3HT:ZnO along and perpendicular to the chain by means of longitudinal field (LF) muon-spin-relaxation (μSR) method to elucidate the intra and inter-chain charge carrier in polymer hybrid P3HT:ZnO. We found the charge carrier transport changes from intra-chain to inter-chain diffusion. One dimensional intra-chain diffusion is observed in the samples at low temperatures, while three dimensional inter-chain is observed at high temperatures.

Preparation of ZnO nanoparticles for blend of P3HT:ZnO nanoparticles:PCBM thin film and its charge carrier dynamics characterization

Recently, many researchers have paid attention to develop active material of solar cell which plays an important role in absorbing solar spectrum. This active material should have an ability to transfer charge carrier resulted from the absorption of solar spectrum. The hybrid organic-inorganic solar cell has been developed due to the combining advantages between organic material Poly(3-hexylthiophene) (P3HT) and fullerene PCBM with inorganic material ZnO nanoparticles. The investigation of charge carrier dynamics in blend P3HT:ZnO nanoparticles:PCBM film as an active material of solar cell devices is an important things to enhance the solar cell performance. The charge carrier dynamics properties is needed to control the morphology of active material to produce an efficient and effective charge dissociation. In this study we synthezed the ZnO nanoparticles by using sol-gel methods. The size of nanoparticles resulted from the reflux process of zinc acetate in methanol by the presence of catalist sodium hyd...

Optical, Structural and Morphological Properties of Ternary Thin Film Blend of P3HT:PCBM:ZnO Nanoparticles

Ternary blend film of conjugated polymer, fullerene and inorganic nanoparticles has intensively studied as active material for high power conversion efficiency (PCE) of hybrid organic-inorganic solar cells. The incorporation of two electron acceptor materials of organic fullerene and inorganic nanoparticles into hybrid with electron donor conjugated polymer is strongly believed can improve the PCE of solar cells by increasing exciton dissociation efficiency due to an increase of interface area between donor and acceptor materials where the positive and negative charges dissociated. We studied optical, structural and morphological properties of ternary thin film containing blend of conjugated polymer poly(3-hexylthiophene (P3HT):fullerene derivative PCBM:Zinc oxide nanoparticles (ZnO-NP) by measuring its optical absorption, crystal structure and film surface morphology. Zinc oxide nanoparticle was prepared by sol-gel method. It has optical absorption below 370 nm and average particle size 40 nm as shown by TEM picture. Ternary thin blend films of P3HT:PCBM:ZnO-NP were prepared by use of spin-coating method. The UV-Vis spectrum of thin film contains absorption peaks originated from contribution of P3HT at wavelengths 520 nm, 550 nm and 600 nm, from contribution of PCBM at 260 nm and 330 nm and from ZnO-NP at wavelengths below 370 nm which confirms that these three materials were well mixed in the films. Its XRD pattern also contains the peaks from each of these three-materials. In this report, we compare surface morphology of thin films of pure P3HT, pure ZnO-NP, blend of P3HT:PCBM, blend of P3HT:ZnO-NP and ternary blend of P3HT:PCBM:ZnO-NP.

Possible Existence of the Stripe Correlations in Electron-Doped Superconducting Cuprates Eu1.85Ce0.15Cu1-yNiyO4+α-δ Studied by Muon-Spin-Relaxation

Partially Ni-substituted electron-doped superconducting cuprates of Eu1.85Ce0.15Cu1-yNiyO4+α-δ (ECCNO) with y = 0, 0.01, 0.02 and 0.05 have been studied by muon-spin-relaxation (mSR) measurements, in order to elucidate whether or not the dynamical stripe correlations of spins and charges exist in electron-doped cuprates. It has been found that the development of the Cu-spin correlation is induced at low temperatures through the Ni substitution and that, for y = 0.02, a muon-spin precession due to a long-range magnetic order has been observed at 10 K. These results suggest a possibility that the stripe model can globally explain the high-Tc superconductivity in both hole- and electron-doped cuprates.

Karakteristik Optik dan Kristal Nanopartikel Magnetit

Oksida besi, nanopartikel magnetit (Fe 3 O 4 ), memiliki sifat yang berbeda dan lebih menarik daripada material bulk-nya. Selain itu, material ini dapat diaplikasikan secara lebih luas dan efektif pada ukuran nanometernya seperti ferrofluids, media penyimpanan data, pigmen warna, dan katalis. Pada penelitian ini telah berhasil dikarakterisasi sifat optik dan struktur kristal dari nanopartikel magnetit dengan menggunakan teknik Spektroskopi UV-Vis dan teknik difraksi sinar-X. Karakterisasi material nanopartikel magnetit berdasarkan variasi suhu sintering, 80 ° C dan 1100 ° C. Berdasarkan hasil karakterisasi UV-Vis diperoleh bahwa energi-gap dari nanopartikel Fe 3 O 4 ini berada pada rentang energi-gap semikonduktor, 0-3 eV. Berdasarkan hasil karakterisasi XRD diperoleh bahwa Variasi suhu sintering menyebabkan berubahan struktur kristal oksida besi yang diperoleh, yaitu magnetit (Fe 3 O 4 ) dengan struktur kubik pada suhu 80 o C, dan hematit (α-Fe 2 O 3 ) dengan struktur hexagonal pada suhu 1100 ° C, sesuai dengan data JCPDS

Influences of Al dopant atoms to the structure and morphology of Al doped ZnO nanorod thin film

We report our work about dependency of Al dopant atoms to the growth process of Al doped ZnO (AZO) nanorod structure. ZnO is one of type metal oxide, which is classified as semiconducting material with direct wide band gap (~ 3.4 eV). This metal oxide is widely used in optoelectronic devices, such as solar cell, gas sensing, and photocatalyst. To produce effective photoelectrode in solar cell devices and high sensitive sensor in gas sensing application, many researchers have been modifying the nanostructure, such as inserting dopant ions, variation in deposition technique and surface modifications. By inserting some dopant ions/atoms, the structure and morphology of ZnO nanorod can be controlled. Nucleation process of nanorod structure which is growth by chemical solution method, are depend on seed layer morphology. We have prepared ZnO nanorod thin film (growth by self-assembly method) with inserting aluminum as dopant atom both in seed layer and nanorod growth solution. The morphology of ZnO nanostructured significantly changes as the existence of aluminum atoms. Based on X-ray diffraction pattern, the wurtzite structures of AZO nanorod still possessed and only affect to the small shift of lattice crystal. A high surface roughness of seed layer can produce wide radius of nanorod, since the nucleation process initiated by seed layer particle size as a template of nanorod arrangement.

Effect of light exposure on the μSR asymmetry of graphene oxide film

Graphene has received a lot of attention due to its promising properties for electronic devices application such as energy storage device. Due to the amount needed for application, graphene oxide is widely used as a precursor to obtain graphene-like material. The GO film is thermally reduced or photoreduced to obtain graphene-like that known as reduced graphene oxide (rGO). We intend to measure microscopic intrinsic charge carrier motion of GO film by means of muon spin rotation relaxation (μSR). We prepared thick film of GO by stacking a lot of GO sheets using 4 mg/ml GO-water dispersion. The rGO material was obtained by thermally reduced GO film at 200°C for 2 hours under argon flowing. We measured zero field (ZF) μSR measurements of GO and rGO from 10 K and 300 K. During the μSR measurement we exposed the light into the samples. We discuss the effect of light exposure on the μSR asymmetry and compare to μSR asymmetry of rGO sample.

Self-Assembly of ZnO-Nanorods and Its Performance in Quasi Solid Dye Sensitized Solar Cells

Zinc oxide (ZnO) nanorods (NRs) were successfully prepared by self-assembly methods using zinc nitrate hexahydrate and hexamethylenetetramine as raw materials. ZnO-NRs were grown on FTO/ZnO seed layer and to enhance dye adsorption it was continued by deposition of titania (TiO2) paste by screen printing method. Deposition time of ZnO-NRs were varied, for 120, 150 and 180 minutes and subsequently stacked with one layer of TiO2 mesoporous. The resulting heterojunction layers of FTO/ZnO-Nrs/TiO2 was then applied as a photoanode in quasi-solid dye sensitized solar cell (QS- DSSC) with polymer gel electrolyte (PGE) as a hole conductor. UV-Vis spectrometer was used to investigate the changes of dye adsorption in photoanode with/without inserting titania mesoporous. Characterizations of scanning electron microscopy (SEM) and X-ray diffraction was carried out and the results shows that increasing the deposition time produces a smaller average grain size, diameter and denser layer of ZnO-nanorods. From current-voltage measurement, higher efficiency (η = 2.53%) was obtained for 120 min ZnO nanorods with short circuit current density (Jsc ) of 2.84 mA/cm2 and open circuit voltage (Voc) of 0.7 V. The combination of TiO2 and ZnO-NRs shows a better performance in solar cells characteristics due to increases of dye adsorption on photoanode and high photogenerated electron transport rate. This work emphasizes an optimum condition of ZnO-NRs in combination with TiO2 mesoporous as an alternative photoanode in QS-DSSC.

Calculation of DSSC parameters based on ZnO nanorod/TiO2 mesoporous photoanode

Photoanode of dye sensitized solar cell (DSSC) plays an important role as electron transport media to accept photogenerated electron from excited state of dye. There are several physical properties that are required from photoanode of DSSC. It should be highly transparent, have large surface area, has a conduction band lower than LUMO of dye molecule, has high charge carrier mobility and finally has a good stability in redox electrolyte process. In this work, DSSC with structure FTO/ZnO nanorod/TiO2 mesoporous/Ru-dye/gel electrolyte/ Pt/FTO has been fabricated. In order to modified the structures of photoanode, ZnO nanorod was grown on aluminium doped ZnO seed layer by variation concentration of Al (0 wt%, 0.5 wt% and 1.0 wt%). Zinc nitrate hexahydrate and hexamethylenetetramine used as raw materials for ZnO nanorod growth solution and deposited by self-assembly methods on FTO/Al doped ZnO seed layer. It is then followed by deposition of titania (TiO2) paste by screen printing methods. DSSC parameters i.e. ideally factor (n), series resistance (RS ), and shunt resistance (RSH ) was derived from current density-voltage (I-V) curve using the simplify equation of ideal diode model. The influences of ZnO photoanode structures to the solar cell performance will be completely discussed.

μSR Study of Charge Carrier Motion in Active Layer P3HT:ZnO:PCBM Hybrid Solar Cells

The so-called hybrid (organic-inorganic) solar cell has been developed due to the combining advantage between organic material such as Poly(3-hexylthiohene)/P3HT and inorganic material such as zinc oxide (ZnO). By adding fullerene derivative (6,6-phenyl-C61-butyric acid methyl ester/PCBM) to the hybrid solar cell, the performance of solar cell is predicted to be increased. We have studied the charge carrier motion in blend of P3HT:ZnO:PCBM using LF-μSR with and without light irradiation to clarify the charge carrier motion in bulk ternary system of hybrid material. We found that charge carrier motion in P3HT:ZnO:PCBM changes from intra-chain to inter-chain diffusion. One-dimensional intra-chain diffusion is observed in the sample at low temperature below 15 K, while three-dimensional inter-chain is observed at high temperature above 25 K.